"it looks like it was caused by a misconfigured nginx transparent proxy. it was redirecting URLs like /x.gif to staging.examiner.com/x.gif. so some sites with tracking images like g.gif?id=XX&crypt=YYZZ got redirected.

and then it just so happened that staging.examiner.com was asking for http auth."

If this is so, then the pop-up seem to be more human error than virus attack.

Singapore will soon exempt local operators, Singapore Pools and Turf Club, from online gambling ban and the sites will be ready in November 2016.

Ministry of Home Affairs explained that a complete ban on remote gambling drives demand and activities
underground, and may create larger incentives for criminal syndicates to
target Singapore."

Yet in a 2012 survey by the National Council on Problem Gambling (NCG) found that those who gamble online have the poorest control.

Source: https://app.msf.gov.sg/Portals/0/Summary/research/EDGD/Gambling%20participation%20survey%202011.pdf
For those who indulged in online gambling, 30.4% said they gambled for a longer period than they planned to, 33.3% gambled with more money than they planned and 29.2% gambled more frequently they planned to.
Will launching the online gambling sites be like opening a Pandora Box that will create more issues in the future?